When cement cracks, it’s a much bigger problem than people realize. The aesthetics are one thing, but eventually, water will find its way into the crack and begin to wear away at the remaining concrete and the steel structures that are embedded for added strength. In an environment that gets cold, that problem is compounded by freeze-thaw action: The water in the crack expands as it freezes, pushing each side just a little bit further apart, only to thaw again and settle further into the crack.
But what if concrete could heal itself? Or asphalt, or even metal? The world might save untold billions of dollars in renovation and repair costs alone, not to mention the reduction in harm to the environment.
As research and development in materials science advance, new ways of constructing buildings are emerging. Some will inevitably find their places in small niches, others might turn out to have broad applicability, but what is certain is that the buildings of the next decade will be stronger, more environmentally friendly, and more cost-efficient than the buildings of the last one.
Here are 6 new materials that could change commercial construction for the better:
1. Mass Timber
Humans have been building with wood since they first moved out of caves, but in modern times, materials like cement and steel have all but supplanted it for tall buildings. There’s a good reason for that: Wood is generally weaker than other materials and it is vulnerable to fire.
Following federal research into more advanced wood building techniques, though, the old dog of the construction industry is getting some new tricks. Mass timber – in which solid wood is panelized and laminated for increased strength and other useful properties – is helping tall wood buildings to appear in cities across America again.
The mass timber category includes several types of laminated timber, most notably cross-laminated timber and glue-laminated timber. Glue-laminated timber is composed of several pieces of lumber that are glued together and is useful for creating strong beams. Cross-laminated timber is made up of pieces of lumber stacked in alternating directions and makes large panels that can support a lot of weight.
Both types of timber are surprisingly fire resistant. The Atlantic reports that the outer layers create a char when burned that helps to insulate the rest of the wood. In fire testing, they have demonstrated the ability to maintain their structural integrity.
Mass timber supports the capture of carbon as the trees grow and its subsequent sequestering in buildings. According to one study in the Journal of Sustainable Forestry, with sustainable forestry techniques, 14 to 31 percent of global emissions could be averted by replacing materials used in buildings and bridges with wood.
2. Self-Healing Materials
Also exciting is the recent developments in self-healing cement. As we mentioned above, even a small crack in a concrete structure can develop into a much bigger, more expensive problem. According to CityLab, materials scientists have recently found a novel way of using living spores to help concrete mend itself when cracks occur!
The solution involves small, water-permeable capsules that can be mixed into wet concrete. Once the concrete sets and dries, the spores exist in suspended animation – just like packets of dry yeast. When a crack opens in the concrete and fills with water, though, they begin to grow and produce calcite, a crystalline form of calcium carbonate found in marble and limestone. The calcite fills the cracks in the concrete and hardens, preventing the crack from getting any wider.
Self-healing concrete could help buildings, tunnels, bridges, and other structures to last longer without significant repairs or replacement. The money that would be saved over the long run is difficult to calculate, as is the reduction in carbon emissions. That said, the costs right now are significantly higher than for regular concrete, and if they don’t come down, this may only be an option for projects that have to last a long time.
3. Air Cleaning Bricks
Indoor air quality (IAQ) is becoming a more important concern for commercial real estate as we gain a better understanding of how built environments affects the health of those who live and work in them. There is no shortage of ways to improve IAQ, but most of them require active energy use to filter the air. That approach emits more carbon and other pollutants into the air over the long term.
Carmen Trudell, assistant professor at Cal Poly San Luis Obispo’s school of architecture and founder of Both Landscape and Architecture, has invented a passive system that makes use of the bricks on the outside of the building to filter out the heavier particles in the air as it enters the space. The concrete bricks funnel air into an internal cyclone filtration section that separates heavy elements and drops them down into a hopper at the base of the wall. Clean air is then pulled into the building, either mechanically or passively, and maintenance can simply remove and empty the hopper on a periodic basis.
In tests, the system removed about a third of fine particulate matter and 100 percent of coarse particles. Better still, Trudell’s system is inexpensive relative to alternative options, and she envisions using them in developing countries.
4. Strand Rods
In Japan, where earthquakes are an unfortunate fact of life, the Komatsu Seiten Fabric Laboratory has covered its head office in a thermoplastic carbon fiber composite that it calls CABKOMA Strand Rod. The composite is covered in inorganic and synthetic fibers and a finish of thermoplastic resin, using tensile strength to create the world’s lightest seismic reinforcement system.
The rods are up to five times lighter than metal wire of the same strength are make for a surprisingly attractive motif. They’re also quite effective – the building is rated well above the conventional performance requirements for seismic reinforcement.
Will strand rods find their way into (or really, onto) buildings around the world? That remains to be seen. The company’s website doesn’t provide details on cost, which is the often deciding factor.
5. Passive Cooling Ceramics
Air conditioning is an energy-intensive process that accounts for an outsized portion of global carbon emissions. Passive cooling methods have been used for centuries, but most are ineffective when it’s very hot outside and many conflict with, rather than support, artificial cooling. Recently, however, students at the Institute for Advanced Architecture of Catalonia’s Digital Matter Intelligent Constructions studio have come up with a facade made of a clay composite and hydrogel that cools buildings the same way our skin cools our bodies.
Our bodies sweat to cool us down. When our skin is wet, heat transfers into the water, and the hottest water particles evaporate, taking the heat away with them. This material functions in the same way. Water collects in the hydrogel droplets that are embedded in the clay composite. As the building heats up, heat is transferred to the water and then lost to evaporation. This effect happens much faster when it is hotter, meaning the system is also responsive to temperature conditions.
The students responsible for the project found that it could produce up to a 6.4 degrees centigrade reduction in temperature over the course of 20 minutes. In ideal conditions, this could lead to a reduction in air conditioning use of 28 percent, which would result in significant savings and reduction in carbon emissions.
Yes, trash. Architects and builders on the cutting edge of the environmental movement are using recycled materials like scrap metal, cardboard, and even plastic bottles to create new buildings with smaller carbon footprints.
Recycled cardboard, for example, is being used to create high-quality cellulose insulation that outperforms insulation made with traditional processes. UltraCell Insulation makes use of a wet process, as opposed to older dry processes that result in contamination and dusty products.
Plastic soda and water bottles have always been recycled, but generally, they can only be used to create new bottles a few times before they need to be disposed of. In the last few decades, plastic bottles have increasingly found new, longer life in the form of PET (polyethylene terephthalate) carpets. The PET in bottles is ideal for making soft, fibrous carpets, and when it reaches the end of its life as a carpet it can be used again in car parts, stuffing, and insulation.
On New York City’s Governors Island, a competition was held recently to see how design can be used to tackle environmental problems. The result was a fascinating mix of art and sustainable design. The five-member Team Aesop laid out five tons of clay to dry, resulting in large, organic cracks. These were then filled with melted-down aluminum cans from a local recycling center to create pavilion panels that are strong, lightweight, and naturally attractive.
As the federal government steps away from leadership on environmental issues, states, private businesses, and consumers are stepping in to fill the gap. Expect to see more new materials finding their way into construction as they become financially sustainable.